Apparatus and methods for removing hydrocarbons and other adherents from sand

Abstract

A system for removing hydrocarbons and other contaminants from sand and/or drill cuttings includes screening large debris from a first loading inlet hopper ( 101 ) to a screen covered receiving hopper ( 102 ) that may contain a chopper and chemical additive nozzles ( 105 ). A first inclined auger ( 104 ) receives the material from hopper ( 102 ) at its lower inlet port and conveys the material upwards dropping it into a hopper ( 106 ) and then to a unit ( 107 ) either of which may include a crasher ( 106 ). Unit ( 107 ) includes an eductor ( 109 ) which feeds the screened and treated sand slurry to desanding units ( 112 ) such as hydro cyclones. The underflow from the desanders is sent to an auger tank's ( 114 ) first compartment ( 113 ) while the overflow is sent to its second compartment ( 115 ) where a flow distributing conduit ( 117 ) that disperses it over the surface of both compartments ( 113 ), ( 115 ). The auger tank ( 114 ) employs horizontal augers ( 116 ) that are arterial both the first and second compartments ( 113 ) and ( 114 ). Second compartment ( 115 ) contains inclined plate separators ( 118 ) and sparging tubes ( 119 ). Overflow from auger tank ( 114 ) is sent to another two compartment separator ( 120 ). The first compartment ( 121 ) which receives the overflow from auger tank ( 114 ) includes a weir-type partition topped by an oil skimmer ( 123 ) connected to a voiding pump ( 125 ) feeding an oil tank ( 124 ) and defining a horizontal gap with the two compartment separator tank bottom as at ( 121 ). Clean water passing through the bottom weir is allowed to spill over the top of the an uppermost weir in the two compartment separator tank ( 120 ) into clean water collection tank ( 122 ) from when it is recycled to other components of the system. The undertow recovered from the auger separation tank ( 114 ) may be further decontaminated by sending it via an inclined conveyor to a serial connection with a second system similar to the one described herein above.

What is claimed: 
     
       1. A system for removing hydrocarbons from sand, the system comprising:
 a first hopper configured to screen large debris from a contaminated sand source; 
 a first inclined auger in fluid communication with the first hopper; 
 a second hopper in fluid communication with the first inclined auger, the second hopper comprising a eductor; 
 a first desanding unit in fluid communication with the second hopper; 
 a first auger tank having a first compartment and a second compartment and a horizontal auger, wherein the first compartment is configured to receive an under flow from the first desanding unit and the second compartment is configured to receive an overflow from the first desanding unit; 
 a second inclined auger in fluid communication with the horizontal auger; and 
 a separator in fluid communication with the first auger tank and configured to receive a hydrocarbon overflow from the first auger tank. 
 
     
     
       2. The system of  claim 1 , further comprising a third hopper in fluid communication with the second inclined auger, wherein the third hopper comprises a second eductor. 
     
     
       3. The system of  claim 2 , further comprising a second desanding unit in fluid communication with the third hopper. 
     
     
       4. The system of  claim 3 , further comprising a second auger tank, the second auger tank comprising a first compartment, a second compartment, and a second horizontal auger, wherein the first compartment is configured to receive an under flow from the second desanding unit and the second compartment is configured to receive an overflow from the second desanding unit. 
     
     
       5. The system of  claim 4 , further comprising a third inclined auger in fluid communication with the second horizontal auger. 
     
     
       6. The system of  claim 5 , wherein at least one of the first and second auger tanks comprises a skimmer. 
     
     
       7. The system of  claim 6 , wherein at least one of the first and second auger tanks comprises at least one air sparing tubes configured to supply a flow of air to at least one of the first and second auger tanks. 
     
     
       8. The system of  claim 7 , wherein at least one of the first and second auger tanks comprises a plurality of inclined plates. 
     
     
       9. The system of  claim 8 , further comprising a surfactant water overflow tank in fluid communication with at least one of the third inclined auger, the separator, and the second auger tank. 
     
     
       10. The system of  claim 9 , further comprising at least one centrifuge in fluid communication with at least one of the separator and the surfactant water overflow tank. 
     
     
       11. The system of  claim 10 , further comprising a solvent storage tank and a flocculant supply tank, wherein the solvent storage tank and flocculant supply tank are configured to supply a solvent and a flocculant to the system. 
     
     
       12. The system of  claim 11 , further comprising at least one heat exchanger. 
     
     
       13. The system of  claim 12 , further comprising a flocculant storage tank in fluid communication with the at least one centrifuge, wherein the flocculant storage tank is configured to supply a flocculant to the system. 
     
     
       14. The system of  claim 13 , wherein at least one of the first and second horizontal auger comprises a plurality of flights having a plurality of lifters. 
     
     
       15. A method of removing hydrocarbons from sand, the method comprising:
 supplying contaminated sand; 
 removing large debris from the contaminated sand; 
 injecting a fluid into the contaminated sand to create a sand/fluid mixture; 
 separating hydrocarbons and the fluid from the mixture, wherein the hydrocarbons and fluid are transferred to an auger tank as an overflow and the sand is transferred to the auger tank as an underflow; 
 settling the sand in the auger tank into a horizontal auger; 
 transferring the sand to an inclined auger; 
 separating hydrocarbons from the fluid in the auger tank; 
 transferring the hydrocarbons from the auger tank to a separator. 
 
     
     
       16. The method of  claim 15 , further comprising:
 transferring the sand from the inclined auger to a hopper, wherein the hopper is configured to inject fluid into the sand to create a second sand/fluid mixture; 
 separating hydrocarbons and fluid from the second sand/fluid mixture, wherein the hydrocarbons and fluid are transferred to a second auger tank as an overflow and the sand is transferred to the second auger tank as an underflow; 
 settling the sand in the second auger tank; 
 separating hydrocarbons from the fluid in the second auger tank; 
 removing the hydrocarbons from the second auger tank; and 
 transferring the sand in the second auger tank to a second inclined auger. 
 
     
     
       17. The method of  claim 16 , further comprising:
 injecting a solvent into the second sand/fluid mixture; and 
 injecting a surfactant into the second sand/fluid mixture. 
 
     
     
       18. The method of  claim 17 , further comprising:
 heating the sand/fluid mixture to about 110° F. 
 
     
     
       19. The method of  claim 18 , further:
 comprising injecting air into at least one of the first and second auger tanks.